package com.etrans.util.base64;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import com.etrans.util.base64.Base64;

/**
 * BASE64编码解码工具包 依赖javabase64-1.3.1.jar
 */

public class Base64Utils {
	/**
	 * 文件读取缓冲区大小
	 */

	private static final int CACHE_SIZE = 1024;

	/***
	 * BASE64字符串解码为二进制数据
	 * 
	 * @param base64
	 * @return
	 * @throws Exception
	 */

	public static byte[] decode(String base64) throws Exception {

		return Base64.decode(base64.getBytes());

	}

	/**
	 * 二进制数据编码为BASE64字符串
	 * 
	 * @param bytes
	 * @return
	 * @throws Exception
	 */

	public static String encode(byte[] bytes) throws Exception {

		return new String(Base64.encode(bytes));

	}

	/**
	 * 将文件编码为BASE64字符串 大文件慎用，可能会导致内存溢出
	 * 
	 * @param filePath
	 *            文件绝对路径
	 * @return
	 * @throws Exception
	 */

	public static String encodeFile(String filePath) throws Exception {

		byte[] bytes = fileToByte(filePath);

		return encode(bytes);

	}

	/**
	 * BASE64字符串转回文件
	 * 
	 * @param filePath
	 *            文件绝对路径
	 * @param base64
	 *            编码字符串
	 * @throws Exception
	 */
	public static void decodeToFile(String filePath, String base64)
			throws Exception {

		byte[] bytes = decode(base64);

		byteArrayToFile(bytes, filePath);

	}

	/**
	 * 文件转换为二进制数组 092
	 * @param filePath
	 * 文件路径 
	 * @return 
	 * @throws Exception
	 * 
	 */

	public static byte[] fileToByte(String filePath) throws Exception {

		byte[] data = new byte[0];

		File file = new File(filePath);

		if (file.exists()) {

			FileInputStream in = new FileInputStream(file);

			ByteArrayOutputStream out = new ByteArrayOutputStream(2048);

			byte[] cache = new byte[CACHE_SIZE];

			int nRead = 0;

			while ((nRead = in.read(cache)) != -1) {

				out.write(cache, 0, nRead);

				out.flush();

			}

			out.close();

			in.close();

			data = out.toByteArray();

		}

		return data;

	}

	/**
	 * 二进制数据写文件 120
	 * @param bytes
	 * 二进制数据 123
	 * @param filePath
	 * 文件生成目录 124
	 */

	public static void byteArrayToFile(byte[] bytes, String filePath)
			throws Exception {

		InputStream in = new ByteArrayInputStream(bytes);

		File destFile = new File(filePath);

		if (!destFile.getParentFile().exists()) {

			destFile.getParentFile().mkdirs();

		}

		destFile.createNewFile();

		OutputStream out = new FileOutputStream(destFile);

		byte[] cache = new byte[CACHE_SIZE];

		int nRead = 0;

		while ((nRead = in.read(cache)) != -1) {

			out.write(cache, 0, nRead);

			out.flush();

		}

		out.close();

		in.close();

	}

}
